1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method thereof, and more particularly relates to a semiconductor device including a plurality of optical fuses for storing adjustment data for adjusting circuit characteristics and a manufacturing method thereof.
2. Description of Related Art
Some semiconductor devices require an adjustment of circuit characteristics by performing fuse trimming in its manufacturing stage. The fuse trimming is performed in a so-called on-the-fly method. For example, in the on-the-fly method, a plurality of optical fuses arranged on an X-axis are selectively blown or trimmed while scanning a laser irradiation position or a semiconductor device on a semiconductor wafer itself in an X-axis direction while a Y-axis is being fixed. Specifically, a laser trimmer emits a laser beam at a timing when the laser irradiation position is right on an X-coordinate of a target optical fuse to blow. A desired optical fuse is thereby blown. When scanning for the designated Y-coordinate is completed, the laser irradiation position is moved to another Y-coordinate, and scanning is performed again in the X-axis direction. The fuse trimming by the on-the-fly method is performed after adjusting or aligning positions of the laser irradiation position with respect to the semiconductor device on the semiconductor wafer. As the number of times of changing the Y-coordinate of the laser irradiation position or the semiconductor device on the semiconductor wafer increases, the proportion of time for moving the Y-axis in a total blowing time of the optical fuse increases, resulting in an increase of the time required for the trimming. In addition, if the number of movements causes a necessity for performing realignment of the laser irradiation position with respect to the semiconductor wafer, the time required for the trimming is further increased.
Meanwhile, the adjustment range of a certain circuit characteristics by the fuse trimming is closely related to the manufacturing maturity level of the semiconductor device. This is because the necessary adjustment range is different between a test production stage with a low maturity level and a mass production stage with a high maturity level. For example, if a characteristic design value of the certain circuit is set at “5” and an adjustable range by the fuse trimming is set at “1” to “9”, all bands from “1” to “9” may be used in the test production stage while only a band from “4” to “6” is a sufficient adjustment range required in the mass production stage.
In this case, if optical fuses for programming “1” to “9” are arranged on the same Y-axis, trimming is completed with a single time of scanning in the X-axis direction regardless of whether it is the test production stage or the mass production stage.
However, there can be a case where the optical fuses cannot be arranged on the same Y-axis due to limitations of layout. In this case, it needs to arrange optical fuses on two or more Y-axes in a distributed manner (see Japanese Patent Application Laid-open H7-273200). However, if such an arrangement is applied, for example, despite the fact that the required adjustment range is as narrow as “4” to “6” in the mass production stage, the Y-coordinate of the optical fuses to blow is distributed to a first Y-coordinate and a second Y-coordinate, and this results in an increase of the trimming time that is the total blowing time of a plurality of optical fuses.